126 
NATJTILOTDEA. 
space of one diameter. The siphuncle appears to be submarginal, 
but owing to the crushed condition of the specimens it is impossible 
to give its position accurately. The surface is entirely covered with 
close-set, irregular, flattisb riblets, divided by interspaces about 
half their width. The riblets are crowded together in some places, 
but they average about five in the space of one line. 
RemarTcs. This species differs from 0. cinctum^ Sow., in its more 
rapid rate of tapering, and in its finer ornamentation, as well as in 
the position of its siphuncle. This last point, however, is rather 
doubtful, owing to the imperfect condition of the majority of 
examples, as already mentioned. 
The Museum is indebted to Mr. J. E. Lee for a large number of 
examples of 0. striolatum collected by himself in the shales over- 
lying the Devonian Limestones at Waddon Barton, near Chudleigh h 
Horizon. Culm-measures ^ (Lower Culm-shale). 
Localities. British. Waddon Barton, near Chudleigh ; Bampton, 
Devonshire. — Foreign. Lautenthal, Harz (Posidonomyenschiefer). 
TRIASSIC SPECIES. 
Orthoceras politum, Klipstein. 
1843. Orthoceras politum, A. v. Klipstein, Beitr. zur geologisch. 
Kenntn. der ostlichen Alpen, p. 144, Taf. ix. f. 6. 
1849. Orthoceratites politum, d’Orbigny, Prodr. de Paleont. Strati- 
graphique, vol. i. p. 179. 
1859. Orthoceratites duhius, Stoppani (pars), Petrifications d’Esino, 
p. 112, pi. xxiv. fi: 1-4. 
1859. Orthoceratites dimidiatus, Stoppani, ibid. p. 113, pi. xxiv. ff. 5-6 
(not of Sowerby). 
1869. Orthoceras politum, Laube, Fauna der Schichten von St. Cassian, 
^ For a list of the fossils, and for other information regarding these deposits, 
see Dr. H. Woodward, in Geol. Mag. {loc. cit.) 
^ Mr. H. B. Woodward (Greol. of England and Wales, 2nd ed. p. 197) 
remarks that “Until the divisions of the Culm-measures are mapped out in 
detail, we must refrain from committing ourselves to any definite correlation. 
He gives the following “ general divisions ” in the Series; — 
f Thick, even -bedded grey grits with 
Lower Coal-measures ? J slates and shales. 
1 Sandstones, grits and shales, with 
Culm-measure J ^ [ beds of culm. 
Series. | Millstone Grit ? Coddon HiU beds (local). 
f Shales, with thin grits, impersistent 
limestones, and occasional beds of 
culm. 
